The present invention relates to the manipulation of liquids in which crystals are grown under outer space conditions, i.e. conditions of weightlessness.
The so called hanging drop method is a method for growing crystals in a drop which is suspended on one side and has an initial volume V1 of an unsaturated solution. Some of the liquid is evaporated so that the drop assumes a smaller volume V2 in which then there is supersaturation of the solved substance and that inturn leads to the crystallization of that substance. This method is of a general nature and it is believed that it is also usable under reduced gravitational force conditions. Moreover, if in fact an experiment along that line is carried out under zero or near zero gravity conditions, the drop that may form under this method may in fact be considerably larger and that in turn means that larger crystals can be grown.
However, contrary to an earth bound application, the method as practiced in outer space must have the following features. The initial solution has to be tightly sealed and stored in this condition prior to the beginning of the experiment. The drop should be produced as much as possible to the utmost extent (actually exclusively) without manual intervention. Following the completion of this process the liquid has to be resealed and stored safely with the grown crystalss whereby the particular liquid that remains has to fill that storage vessel completely because gas bubbles or the like have to be avoided; otherwise the crystals that have been produced in outer space could easily be destroyed on landing. Moreover, it is of course of great practical significance to have a large number of such processes conducted in a smaller space as possible as is well known space is a rare commodity in outer space experiments. The state of the art includes German patent applications 3,615,541 and 1,129,717 (the latter has a U.S. couterpart--Ser. No. 680,261, filed Aug. 26, 1957). And Journal of Crystal Growth, vol. 76 (1986) p. 681 to 693.